The efficient production of crops requires that seed planters meet certain primary design objectives which are: creating a furrow having an accurate planting depth and preferably providing soil having a reasonably high moisture content for early germination; accurate seed spacing; and seed to soil contact. This invention is primarily concerned with the furrow forming aspect of the planter.
A known seed planter utilizes a conventional pair of rotatably mounted, generally flat, disk openers that substantially contact each other where the disks enter the ground and diverge apart rearwardly and upwardly. The disks are supported on a frame which is connected to a tool bar of a mobile power source by a parallel support linkage so that the frame is maintained in a generally horizontal position parallel to the ground despite varying ground contours. A down-pressure spring arrangement extends between the upper and lower links of the parallel linkage. Depending upon the relative lever arms of the upper and lower links, the springs can apply varying amounts of upward or downward pressure to the linkage, and thereby decrease or increase the force applied to the disks to insure that they properly penetrate the soil.
To facilitate efficient furrow formation under different soil conditions, the present invention provides an arrangement which permits quick and easy adjustment of the aforementioned pressure without the use of any tools.